The present patent application/patent is related to U.S. Pat. Nos. 6,251,156 and 6,582,491, both of which relate to the production of iron in a duplex furnace, as well as U.S. Pat. No. 8,262,766, which relates to the production of ferro-chrome.
U.S. Pat. No. 6,251,156, in general, provides a method for the operation of a rotary hearth furnace in conjunction with an electric melter for the production of high purity iron product having a range of silicon and manganese, with low sulfur and phosphorus content. The method includes producing a high purity iron product and a range of carbon content product from iron oxide and carbon bearing compacts, including the steps of providing a furnace for the direct reduction of iron oxide and carbon bearing compacts, pre-reducing iron and carbon bearing compacts in a furnace having a rotary hearth surface, and producing intermediate carbon containing metallized iron. An electric melter furnace is utilized for receiving intermediate carbon containing metallized iron from the pre-reducing step, which is fed directly and continuously into a central interior area of the electric melter, with heating of the carbon containing metallized iron in the electric melter under elevated temperatures of about 1300° C. to about 1700° C., minimizing the ingress of air or other undesirable gases, such as oxygen, in the melting step while maintaining elevated temperatures, and removing high purity liquid iron product from the electric melter. The method provides a high iron content product having a specified range of carbon, silicon, and manganese percentages, with low sulfur and phosphorus content. There is significant reduction of silicon oxides, and reduction of manganese oxides in the product. An extremely desirable high iron content product is thereby produced for use by the steelmaking industry.
U.S. Pat. No. 6,582,491, in general, provides a method for the operation of a moving hearth furnace in conjunction with an electric melter for the production of high purity iron product having a range of silicon and manganese, with low sulfur and phosphorus content. The method includes producing high purity iron product and a range of carbon content product from iron oxide and carbon bearing agglomerates, including the steps of providing a furnace for the direct reduction of iron oxide and carbon bearing agglomerates, pre-reducing the iron and carbon bearing agglomerates in a furnace having a moving hearth surface, and producing intermediate carbon containing metallized iron. An electric melter furnace is utilized for receiving the intermediate carbon containing metallized iron from the pre-reducing step, which is fed directly and continuously into a central interior area of the electric melter, with heating of the carbon containing metallized iron in the electric melter under elevated temperatures of about 1300° C. to about 1700° C., minimizing the ingress of air or other undesirable gases, such as oxygen, in the melting step while maintaining elevated temperatures, and removing high purity liquid iron product from the electric melter. The method provides a high iron content product having a specified range of carbon, silicon, and manganese percentages, with low sulfur and phosphorus content. There is significant reduction of silicon oxides, and reduction of manganese oxides in the product. Again, an extremely desirable high iron content product is thereby produced for use by the steelmaking industry.
U.S. Pat. No. 8,262,766, in general, provides a method for reducing a chromium containing material at a high chromium reduction degree. In the method, a mixture of a feedstock containing chromium oxide and a carbonaceous reductant is heated and reduced by radiation heating in a moving hearth furnace. The average rate of raising the temperature of the mixture in the reduction is preferably about 13.96° C./s or higher in the period from the initiation of the radiation heating of the mixture until the mixture reaches about 1,114° C.
What are still needed in the art, however, are methods and systems for the operation of a rotary hearth furnace in conjunction with an electric melter for the production of a high purity ferro-chrome product having a range of silicon content, with low sulfur and phosphorus content.